Multiple criminological theories predict that attitudes toward delinquency should affect an individual’s delinquent behavior. Criminological research, however, has not sufficiently incorporated social psychological theory predicting the reverse causal relationship, and tends to suffer from important methodological limitations. The present study addresses these issues using longitudinal data from the New Hampshire Youth Study (N = 626). After using latent variable models to demonstrate the discriminant validity of attitudinal and behavioral measures, it uses structural equation models to examine whether attitudes are stronger predictors of behavior or vice versa. Net of controls, results provide qualified support for a reciprocal relationship but suggest that behavior affects attitudes much more than attitudes affect behavior. We conclude by discussing the implications of these findings for future research and for interventions aimed at controlling delinquency.